Numerical studies on four-engine rocket exhaust plume impinging on flame deflectors with afterburning

This paper studies the four-engine liquid rocket flow field during the launching phase.Using threedimensional compressible Navier-Stokes equations and two-equation realizable k-epsilon turbulence model,an impact model is established and flow fields of plume impinging on the two different shapes of flame deflectors,including wedge-shaped flame deflector and cone-shaped flame deflector,are calculated.The finite-rate chemical kinetics is used to track chemical reactions.The simulation results show that afterburning mainly occurs in the mixed layer.And the region of peak pressure occurs directly under the rocket nozzle,which is the result of the direct impact of exhaust plume.Compared with the wedgeshaped flame deflector,the cone-shaped flame deflector has great performance on guiding exhaust gas.The wedge-shaped and cone-shaped flame deflectors guide the supersonic exhaust plume away from the impingement point with two directions and circumferential direction,respectively.The maximum pressure and temperature on the wedge-shaped flame deflector surface are 37.2%and 9.9%higher than those for the cone-shaped flame deflector.The results provide engineering guidance and theoretical significance for design in flame deflector of the launch platforms.

Application study on plasma ignition in aeroengine strut–cavity–injector integrated afterburner

To increase the thrust-weight ratio in next-generation military aeroengines,a new integrated afterburner was designed in this study.The integrated structure of a combined strut–cavity–injector was applied to the afterburner.To improve ignition characteristics in the afterburner,a new method using a plasma jet igniter was developed and optimized for application in the integrated afterburner.The effects of traditional spark igniters and plasma jet igniters on ignition processes and ignition characteristics of afterburners were studied and compared with the proposed design.The experimental results show that the strut–cavity–injector combination can achieve stable combustion,and plasma ignition can improve ignition characteristics.Compared with conventional spark ignition,plasma ignition reduced the ignition delay time by 67 ms.Additionally,the ignition delay time was reduced by increasing the inlet velocity and reducing the excess air coefficient.This investigation provides an effective and feasible method to apply plasma ignition in aeroengine afterburners and has potential engineering applications.

NUMERICAL MODELING OF TURBULENTEVAPORATING GAS-DROPLET TWO-PHASE FLOWS IN AN AFTERBURNER DIFFUSOR OF TURBO-FAN JET ENGINES

The two-dimensional turbulent evaporating gas-droplet two-phase flows in an afterburner diffusor of turbo-fan jet engines are simulated by the k-ε turbulence model and the particle trajectory model. Comparison of predicted gas velocity and temperature distributions with experimental results for the cases without liquid spray shows pretty good agreement. Gas-droplet two-phase flow predictions give plausible droplet trajectories, fuel-vapor concentration distribution, gas-phase velocity and temperature field in presence of liquid droplets. One run of computation with this method is made for a particular afterburner. The results indicate that the location of the atomizers is not favorable to flame stabilization and combustion efficiency. The proposed numerical modeling can also be adopted for optimization design and performance evaluation of afterburner combustors of turbo-fan jet engines.

AfterBurn 3 for 3ds max

AfterBurn是一款在电影、广告、游戏等领域广泛应用的软件3ds max的强大特效插件，它以在真实性表现上的强大实力著称，是在3ds中制作真实的云雾、烟雾、爆炸等特效时不可或缺的工具．

AfterBurn 2.5——云雾大师

你想过在3DS MAX 4里创建真实的云雾效果吗?AfterBurn 2.5能帮助你实现这个梦想。以前,在没有这个插件的时候,我们一般也使用粒子系统制作云雾效果,但贴图法往往不很真实。如今,有了AfterBurn 2.5,我们使用这个插件就可以将3DS MAX从粒子、灯光到环境编辑器在内的全套的特效系统动用起来,一起为我们实现喷云吐雾的效果。

MAX的烟火插件AfterBurn3．2升级

MAX插件AfterBurn32升级．新版新增功能包括：修复了一些使用者报告的bugs；增加了更多DCP的与FR_stage1渲染器、PF粒子系统、Thinking Particle粒子系统的协同性；新的教程文件和修订了的练习视频。

基于结构响应的舱室内爆TNT等效方法

[目的]旨在揭示爆轰产物后燃烧效应对封闭空间中爆炸载荷的影响规律。[方法]通过往封闭舱室中充入氮气来抑制爆轰产物燃烧,开展在空气和氮气两种不同气体环境下封闭舱室内TNT爆炸响应试验,记录温度、压力变化历程和靶板中心点残余挠度,建立基于无量纲载荷参数的靶板变形与炸药释放能量之间的关系,并提出考虑后燃烧效应的封闭空间TNT等效方法。[结果]结果发现,由于爆轰产物燃烧能量释放量不同,在氮气环境中,封闭空间内爆炸压力、温度和靶板动态响应明显低于空气环境。内爆载荷分析需计入TNT爆炸产物燃烧释放的能量及其增强效应。[结论]与现有基于准静态压力的TNT当量计算方法进行的比较表明,所提基于结构响应的舱室内爆TNT等效方法具有合理性和良好的适用性。

Effects of main components on energy output characteristics of thermobaric explosive——A case study of typical formulations

As a kind of high-efficiency explosive with compound destructive capability, the energy output law of thermobaric explosives has been receiving great attention. In order to investigate the effects of main components on the explosive characteristics of thermobaric explosives, various high explosives and oxidants were selected to formulate five different types of thermobaric explosive. Then they were tested in both open space and closed space respectively. Pressure measurement system, high-speed camera,infrared thermal imager and multispectral temperature measurement system were used for pressure,temperature and fireball recording. The effects of different components on the explosive characteristics of thermobaric explosive were analyzed. The results showed that in open space, the overpressure is dominated by the high explosives content in the formulation. The addition of the oxidants will decrease the explosion overpressure but will increase the duration and overall brightness of the fireball. While in closed space, the quasi-static pressure formed after the explosion is positively correlated with the temperature and gas production. In addition, it was found that the differences in shell constraints can also alter the afterburning reaction of thermobaric explosives, thus affecting their energy output characteristics. PVC shell constraint obviously increases the overpressure and makes the fireball burn more violently.

Optimal scheduling of a township integrated-energy system using the adjustable heat-electricity ratio model

With the expansion and implementation of rural revitalization strategies,there is a constant need for new energy sources for the construction of new townships.Consequently,integrated energy systems with the interconnection and interaction of multiple energy sources are developing rapidly.Biomass energy,a renewable green energy source with low pollution and wide distribution,has significant application potential in integrated energy systems.Considering the application of biomass energy in townships,this study established an integrated biomass energy system and proposed a model to optimize its operation.Lowest economic cost and highest clean energy utilization rate were considered as the objective functions.In addition,a plan was suggested to adjust the heat-electricity ratio based on the characteristics of the combined heat and power of the biomass.Finally,a simulation analysis conducted for a town in China was discussed,demonstrating that the construction of a township integrated-energy system and the use of biomass can significantly reduce operating costs and improve the energy utilization rate.Moreover,by adjusting the heat-electricity ratio,the economic cost was further reduced by 6.70%,whereas the clean energy utilization rate was increased by 5.14%.

一体化加力燃烧室热态流场与特性数值研究

为满足新一代航空发动机的高推重比需求,提出一种支板与混合器一体化加力燃烧室方案,采用数值仿真方法,对比分析进口马赫数Ma (0.3~0.45),涵道比B (0.25~0.37)和不同飞行高度H(0~20 km)对加力燃烧室热态流场特性的影响。研究表明:在研究参数范围内,进口马赫数增大,壁式稳定器回流区及下游区域的燃气温度受到影响,区域内燃气温度逐渐升高,沿程径向温度不均匀性逐渐减小,总压损失增大,燃烧效率逐渐下降,但出口燃烧效率仍基本高于0.90;进口涵道比B增大,壁式稳定器下游及中心锥轴线位置的燃气温度开始下降,沿程燃气总压损失增大,燃烧效率随之升高,B从0.25增大至0.28时,燃烧效率提升较大,继续增大涵道比,燃烧效率提升较少;随着飞行高度升高,整体燃烧效率逐渐下降,在0 km和11 km飞行高度之间燃烧效率下降较少,而在20 km飞行高度时燃烧效率下降相对明显。

部分旋流对加力燃烧室流动和燃烧性能的影响

为改善先进加力/冲压燃烧室燃烧组织困难等问题,采用设置进口部分旋流,在燃烧室中产生局部离心力来增强油气掺混和加速火焰传播。通过数值模拟和试验的方法,研究了不同旋流进口位置及角度下部分旋流加力/冲压燃烧室的流动特性、燃烧效率及值班点火火焰发展过程。研究发现:多区域旋流进口与不同旋流角度的组合会使流动损失增大,但可以在燃烧室建立一个局部超重力场,增强油气掺混和加速点火过程火焰传播。相比于无旋流,旋流进口可以提高值班火焰传播速度;旋流进口最高可提升2.35%的燃烧效率。

坑道内爆炸条件下温压炸药的爆炸特性及其影响因素

温压炸药在坑道内爆炸时会产生多种毁伤元,对坑道内人员和设备造成严重威胁。基于不同药量的温压炸药爆炸试验,对坑道内爆炸条件下温压炸药的爆炸特性开展了研究,分析了爆炸热效应演化特征、冲击波传播规律和氧浓度降低情况,讨论了坑道对铝粉后燃的约束作用规律以及形成高烈度后燃效应的药量条件。研究表明:温压炸药火球辐射亮度高于TNT,且其火球温度峰值超过TNT温度峰值的1.3倍。在火球演化过程中,火球在后燃阶段的温度峰值较火球形态刚稳定时提升超过10%。在冲击波传播规律方面,超压峰值与正压时间的TNT当量系数分别约为1.4与1.65。另外,铝粉后燃产生的压缩波对冲击波能够形成多种补充效果,陡峭升压的压缩波能够使冲击波峰值升高,持续时间长但升压速率慢的压缩波能够限制冲击波的衰减,延长整体正压作用时间。受坑道约束作用,温压炸药爆炸火球将与坑道壁面发生相互作用,进而提高铝粉的燃烧烈度。当温压炸药质量立方根与坑道直径的比值大于0.28 kg^(1/3)/m时,将产生高烈度后燃效应。

密闭建筑温压炸药内爆炸后燃效应

温压炸药爆炸具有显著的后燃效应,在密闭空间内爆炸呈现多重毁伤效应,但后燃效应引起的多毁伤元耦合效应,以及后燃增强效应的量化分析尚不明确。基于搭建的大尺寸密闭建筑,开展不同药量下温压炸药及LiF替代铝粉炸药的内爆试验研究,对温度、冲击波超压、准静态压力及氧浓度进行测试,分析内爆条件下不同毁伤元的时空变化特征,结合LiF替代铝粉炸药爆炸的对比试验,阐明了密闭建筑内爆炸毁伤元的分布特点以及铝粉后燃效应对温度、冲击波超压、准静态压力和氧浓度变化的影响规律。研究结果表明:密闭空间内爆下热效应和压力效应在角落边界处得到显著增强,其中全过程比冲量在边界处增强了2.2~2.5倍;铝粉后燃反应可显著增强温度、冲击波超压、准静态压力和氧气消耗量,当药量达到300 g下,铝粉后燃烧导致爆炸冲击波超压峰值提高1.2倍,温度峰值提高6.4倍,准静态压力提高2.2倍,氧浓度消耗提高2.8倍。

封闭空间内爆载荷下结构响应试验及仿真研究

TNT在封闭空间内爆炸会发生燃烧反应并释放大量的能量,这些附加能量会对内爆载荷起到增强作用,为分析封闭空间内爆炸载荷作用下的结构动态响应。开展封闭空间爆炸试验,通过试验数据对称性验证,说明试验中压力测试结果准确可靠;然后开展数值计算研究,并探讨板厚、屈服应力和边界约束3个因素对靶板结构动态响应的影响。数值计算与试验结果的准静态压力吻合较好,靶板中心点初始峰值位移和最终位移的误差均小于5%,验证数值计算方法的可靠性;靶板中心点初始峰值位移和最终位移增大比例与板厚减小比例相当;靶板中心点初始峰值位移减小比例约为屈服应力增大比例的0.2倍,而最终位移的减小比例约为屈服应力增大比例的0.4倍。所采用的数值计算方法能够很好地模拟结构在封闭空间爆炸载荷作用下的响应,可为舰船抗爆结构设计提供一定参考。

脉冲爆震外涵加力涡扇发动机总体性能研究

为研究外涵装有脉冲爆震燃烧室(PDC)的混合排气涡扇发动机性能,建立其性能模型。研究了隔离段总压恢复系数和外涵循环参数对PDC特性和整机性能的影响;分析了发动机性能参数对部件参数的敏感性;在相同设计循环参数下与传统加力涡扇发动机性能进行了对比。结果表明:提高隔离段总压恢复系数能够增大PDC增压比,提升发动机性能;风扇压比一定,涵道比增大,发动机耗油率和单位推力增大;风扇压比增大,涵道比在0.2~0.4时,单位推力先增大后减小,涵道比在0.4~0.5时,单位推力先增大后基本不变,涵道比在0.5~0.9时,单位推力一直增大,但增幅逐渐减小。不同涵道比下耗油率随风扇压比增大一直减小;发动机性能对直接影响外涵气流状态参数的部件参数敏感性高;由于PDC的增压特性,脉冲爆震外涵加力发动机仅利用外涵部分气流组织燃烧就可使单位推力与传统加力涡扇发动机相当,且耗油率在设计点降低27.7%,非设计点降低12.8%~26.8%。

一体化加力燃烧室燃油自燃特性研究

为探索一体化加力燃烧室内发生自燃现象的规律,以一体化支板中的燃油喷射系统为研究对象,采用高速摄影法拍摄了燃油在高温来流条件下的自燃火焰,重点分析了一体化加力燃烧室来流温度、来流速度、余气系数、燃油喷嘴类型等因素对于燃油自燃特性的影响规律。结果表明:提高加力燃烧室来流温度使得燃油更容易发生自燃,当来流温度超过1 200 K时所有工况下燃油都可以发生自燃;提高加力燃烧室来流速度有利于抑制自燃,使得燃油自燃延迟距离增大;贫油情况下燃油颗粒可以从环境中吸收更多的热量,自燃延迟距离减小;雾化效果好的锥形雾化喷嘴容易发生自燃,雾化效果差的直射式喷嘴相对稳定。研究结果为一体化加力燃烧室的供油系统和点火系统的设计提供初步的参考价值。

强余旋一体化支板稳定器雾化特性研究

本文在高温高速强余旋来流条件下,初步探索了带尾缘方案下支板一体化喷油稳定器结构的油气掺混工作特性,为后期研究回流区卷吸量和稳焰特性做准备。使用平面激光诱导荧光(PLIF)、平面米散射(PMIE)、相位多普勒粒子分析仪(PDPA)等设备,以航空煤油为介质,在来流温度300~1050 K,马赫数0.15~0.45,液气动量比20~250,来流角度-15°~15°,供油压差0.2~1.8 MPa等条件下,探究了来流参数、气液动量比、韦伯数等多因素对射流轨迹、雾化粒径的影响规律。试验表明:上喷式支板尾缘一体化喷油稳定器的整体射流轨迹与横向射流结构较类似,液气动量比越大,射流穿透深度增加越明显;气体韦伯数的影响机制比较复杂,当其增大时,射流穿透深度呈下降趋势,是来流与射流之间的压差力和各向剪切力的作用使得表面波增长迅速,不稳定性增强,叠加气液动量交换增大的结果;气流与支板夹角的正逆变化,即余旋角变化,使得垂直于来流气体方向的速度分量产生变化,流道内稳定器的喉部效应增大了湍流度,使射流轨迹变粗糙,穿透深度变短;通过分析PDPA数据,在射流覆盖区域呈现出了整体的粒径分布情况,显示出了射流轨迹、表面波主导破碎区、二次雾化区、粒径稳定区间的关系。

高温高速来流条件下扇形喷嘴雾化特性研究

为了探索扇形喷嘴在加力燃烧室应用的可行性,采用Mie散射和PLIF激光测量系统对其在高温高速环境中的雾化特性开展了研究。获得了在不同来流温度、来流马赫数以及燃油流量条件下燃油轨迹变化规律、蒸发距离及气液两相分布特性,并拟合了穿透深度经验公式。试验结果表明:在来流温度850~1 250 K,马赫数为0.15~0.35,燃油流量6~14 g/s的工况下,(1)温度升高,燃油穿透深度减小,蒸发距离变短;(2)马赫数增加,燃油穿透深度减小,蒸发距离变长;(3)燃油流量增加,燃油穿透深度增加,对蒸发距离影响较小;(4)气相燃油分布区约为液相的6倍。

基于详细化学反应机理的加力燃烧室湍流燃烧数值研究

为了深入理解加力燃烧室的湍流燃烧特性,开展了燃油配置和内涵进气参数对燃烧性能影响的二维数值研究.基于燃油喷嘴和火焰稳定器附近涡系结构和涡量探究了油气掺混过程,通过燃烧室压力、温度、流速、湍动能等分布情况揭示了流场和温度场的组织状况,阐述了燃油、氧气的分布情况以及主要燃烧产物的生成机制,揭示了燃烧室典型截面温度和流速的分布特征.结果表明:燃油总流量增加整体上增强了三圈的燃烧性能,内涵进气参数下降减弱了内圈和中圈的燃烧性能,较高内涵进气压力是保障高效燃烧最关键的运行措施.